We request funding for a new Orbitrap Velos ETD (Thermo) and plan to integrate this in the Proteome Exploration Laboratory (PEL) of the Beckman Institute at the California Institute of Technology (Caltech). The PEL was established in 2007 and is the only resource center at Caltech where mass spectrometry-based proteome analyses can be performed. The PEL collaborates with students and postdoctoral fellows of the Caltech community to enable their proteomics-related research. The main long-term objective of the PEL is to enable the in-depth elucidation and quantification of proteomes and subproteomes to gain fundamental insights into biological regulatory mechanisms. A common experimental paradigm is to monitor global protein changes that occur after either treating cells with drugs or natural ligands or subjecting them to an environmental or genetic perturbation. Novel methods are constantly being developed to achieve this goal. We request funding for two main reasons. First, demand in the Caltech community has overwhelmed our current suite of instruments. Second and more importantly, technological limitations of our current instruments are hampering the progress of NIH-funded projects in the laboratories of our collaborators. The Orbitrap Velos ETD has the ability to transmit ions with higher efficiency and scan faster than the first generation instruments, thus increasing overall sensitivity. In addition, higher energy C-trap dissociation (HCD) and electron transfer dissociation (ETD) offer complementary fragmentation techniques not available to us, but essential for the progress of the proposed projects. Moreover, the Proxeon Easy nanoHPLC with nanoESI source that we acquired in anticipation of purchasing an Orbitrap Velos allows for rapid switching between 1D and 2D LC separations, which is critical given the great range in complexity of samples that are analyzed at the PEL. To demonstrate our commitment to this application, the PEL has already purchased essential auxiliary equipment for the Orbitrap Velos and will use money obtained from private sources to cover the difference between the maximum allowable funding under this grant mechanism and the purchase price of the Orbitrap Velos. An Orbitrap Velos mass spectrometer coupled with the Proxeon LC system and source, working in concert with our existing bioinformatics pipeline, will play a vital role in advancing projects that span a broad range of fundamental and applied studies that include cancer, neurological disorders (such as Alzheimer's disease, Parkinson), autoimmune diseases, vascular diseases and infections. Fundamental insights in any of these areas will help to prevent and/or cure diseases that have previously been considered incurable.